分类: LINUX
2011-11-20 15:01:07
EXPORT_SYMBOL标签内定义的函数或者符号对全部内核代码公开,不用修改内核代码就可以在内核模块中直接调用,即使用EXPORT_SYMBOL可以将一个函数以符号的方式导出给其他模块使用。
Linux symbol export method:
[1] If we want export the symbol in a module, just use the EXPORT_SYMBOL(xxxx) in the C or H file.
And compile the module by adding the compile flag -DEXPORT_SYMTAB.
Then we can use the xxxx in the other module.
[2] If we want export some symbol in Kernel that is not in a module such as xxxx in the /arch/ppc/fec.c.
Firstly, define the xxxx in the fec.c;
Secondly, make a new file which contain the "extern" define the xxxx(for example, extern int xxxx);
Lastly, in the ppc_ksyms.c we includes the new file, and add the EXPORT_SYMBOL(xxxx).
Then we can use the xxxx.
使用时注意事项:
在使用EXPORT_SYMBOL 的.c文件中 需要 #include
// 先写函数
func_a ()
{
}
//再使用EXPORT_SYMBOL
EXPORT_SYMBOL(func_a);